Unraveling Stereochemical Structure-Activity Relationships of Sesquiterpene Lactones for Inhibitory Effects on STAT3 Activation.

Sesquiterpene lactones, a class of natural compounds abundant in the Asteraceae family, have gained attention owing to their diverse biological activities, and particularly their anti-proliferative effects on human cancer cells. In this study, we systematically investigated the structure-activity relationship of ten sesquiterpene lactones with the aim of elucidating the structural determinants for the STAT3 inhibition governing their anti-proliferative effects. Our findings revealed a significant correlation between the STAT3 inhibitory activity and the anti-proliferative effects of sesquiterpene lactones in MDA-MB-231 breast cancer cell lines. Among the compounds tested, alantolactone and isoalantolactone emerged as the most potent STAT3 inhibitors, highlighting their potential as candidates for anticancer drug development. Through protein-ligand docking studies, we revealed the structural basis of STAT3 inhibition by sesquiterpene lactones, emphasizing the critical role of hydrogen-bonding interactions with key residues, including Arg609, Ser611, Glu612, and Ser613, in the SH2 domain of STAT3. Furthermore, our conformational analysis revealed the decisive role of the torsion angle within the geometry-optimized structures of sesquiterpene lactones in their STAT3 inhibitory activity (R=0.80, p<0.01). These findings not only provide preclinical evidence for sesquiterpene lactones as promising phytomedicines against diseases associated with abnormal STAT3 activation, but also highlight the importance of stereochemical aspects in their activity.

Cheminformatic Read-Across Approach Revealed Ultraviolet Filter Cinoxate as an Obesogenic Peroxisome Proliferator-Activated Receptor γ Agonist.

This study introduces a novel cheminformatic read-across approach designed to identify potential environmental obesogens, substances capable of disrupting metabolism and inducing obesity by mainly influencing nuclear hormone receptors (NRs). Leveraging real-valued two-dimensional features derived from chemical fingerprints of 8435 Tox21 compounds, cluster analysis and subsequent statistical testing revealed 385 clusters enriched with compounds associated with specific NR targets. Notably, one cluster exhibited selective enrichment in peroxisome proliferator-activated receptor γ (PPARγ) agonist activity, prominently featuring methoxy cinnamate ultraviolet (UV) filters and obesogen-related compounds. Experimental validation confirmed that 2-ethoxyethyl 4-methoxycinnamate, an organic UV filter cinoxate, could selectively bind to PPARγ (Ki = 18.0 µM), eliciting an obesogenic phenotype in human bone marrow-derived mesenchymal stem cells during adipogenic differentiation. Molecular docking and further experiments identified cinoxate as a potent PPARγ full agonist, demonstrating a preference for coactivator SRC3 recruitment. Moreover, cinoxate upregulated transcription levels of genes encoding lipid metabolic enzymes in normal human epidermal keratinocytes as primary cells exposed during clinical usage. This study provides compelling evidence for the efficacy of cheminformatic read-across analysis in prioritizing potential obesogens, showcasing its utility in unveiling cinoxate as an obesogenic PPARγ agonist.

Discovery of PPARγ and glucocorticoid receptor dual agonists to promote the adiponectin and leptin biosynthesis in human bone marrow mesenchymal stem cells.

Adiponectin and leptin are major adipocytokines that control crosstalk between adipose tissue and other organ systems. Hypoadiponectinemia and hypoleptinemia are associated with human metabolic diseases. Compounds with adipocytokine biosynthesis-stimulating activities could be developed as therapeutics against diverse metabolic conditions. In phenotypic screening with human bone marrow mesenchymal stem cells (hBM-MSCs), (E)-4-hydroxy-3-(3-(4-hydroxy-3-methoxyphenyl)acryloyl)-6-methyl-2H-pyran-2-one (1) was identified to increase adiponectin biosynthesis during adipogenesis and simultaneously to stimulate leptin production. Using the compound 1 structure, the structure-activity relationship study was performed to discover more potent compounds stimulating both adiponectin and leptin production. (E)-3-(3-(2-fluoropyridin-4-yl)acryloyl)-4-hydroxy-6-methyl-2H-pyran-2-one (11) exhibited the most potent adiponectin (EC50, 2.87 µM) and leptin (EC50, 2.82 µM) biosynthesis-stimulating activities in hBM-MSCs. In a target identification study, compound 11 was characterized as a dual modulator binding to both peroxisome proliferator-activated receptor (PPAR) γ and glucocorticoid receptor (GR). This study provides a novel pharmacophore for PPARγ/GR dual modulators with therapeutic potential against human metabolic diseases.

Hepatic TREM2+ macrophages express matrix metalloproteinases to control fibrotic scar formation.

Liver cirrhosis is characterized by the extensive deposition of extracellular matrix such as fibril collagen, causing dysfunction and failure of the liver. Hepatic macrophages play pivotal roles in the transition from inflammatory to restorative properties upon hepatic injury. In particular, scar-associated macrophages (SAMacs) control liver fibrosis with the representative expression of matrix metalloproteinase (MMP). However, the heterogenic SAMac population has not been well characterized yet. This study profiled heterogeneous liver macrophages using public databases of single-cell transcriptomics and found T-cell immunoglobulin and mucin containing (TIM)4- macrophages exhibited elevated expression of MMPs. Scar-associated triggering receptor expressed on myeloid cells (TREM)2 was positively correlated with MMP expression, suggesting that TREM2+ subsets exert their fibrotic role via MMPs. During the progression of diet-induced nonalcoholic steatohepatitis and drug-induced liver cirrhosis, monocyte-derived TREM2+ macrophages accumulate in the liver with the distinct expression of MMPs. A noticeable expansion of MMP- and TREM2- double positive macrophages was observed in fibrotic scar regions. Consistently, the analysis of single-cell transcriptomics for human cirrhotic livers supported the theory that TREM2+ SAMacs are strongly associated with MMPs. The results could expand the understanding of liver fibrosis and SAMac, offering potential therapeutic approaches for liver cirrhosis.

Design, Synthesis, and Biological Activity of l-1'-Homologated Adenosine Derivatives.

On the basis of the previously reported polypharmacological profile of truncated d-1'-homologated adenosine derivatives [J. Med. Chem.2020, 63, 16012], the l-nucleoside analogues were synthesized using computer-aided design and evaluated for biological activity. The target molecules were synthesized from d-ribose via the key intramolecular cyclization of the monotosylate and Mitsunobu condensation. The peroxisome proliferator-activated receptor (PPAR) binding activities of l-nucleoside analogue 2d (K i = 4.3 µM for PPARγ and 1.0 µM for PPARδ) were significantly improved in comparison with those of the d-nucleoside compound 1 (11.9 and 2.7 µM, respectively). In addition, the l-nucleosides showed more potent adiponectin-secretion-promoting activity than the d-nucleoside analogues.

Galangin 3-benzyl-5-methylether derivatives function as an adiponectin synthesis-promoting peroxisome proliferator-activated receptor γ partial agonist.

The upregulation of adiponectin production has been suggested as a novel strategy for the treatment of metabolic diseases. Galangin, a natural flavonoid, exhibited adiponectin synthesis-promoting activity during adipogenesis in human bone marrow mesenchymal stem cells. In target identification, galangin bound both peroxisome proliferator-activated receptor (PPAR) γ and estrogen receptor (ER) ß. Novel galangin derivatives were synthesized to improve adiponectin synthesis-promoting compounds by increasing the PPARγ activity of galangin and reducing its ERß activity, because PPARγ functions can be inhibited by ERß. Three galangin 3-benzyl-5-methylether derivatives significantly promoted adiponectin production by 2.88-, 4.47-, and 2.76-fold, respectively, compared to the effect of galangin. The most potent compound, galangin 3-benzyl-5,7-dimethylether, selectively bound to PPARγ (Ki, 1.7 µM), whereas it did not bind to ERß. Galangin 3-benzyl-5,7-dimethylether was identified as a PPARγ partial agonist in docking and pharmacological competition studies, suggesting that it may have diverse therapeutic potential in a variety of metabolic diseases.

Sunscreen filter octocrylene is a potential obesogen by acting as a PPARγ partial agonist.

Octocrylene (OC) is an extensively prescribed organic ultraviolet B filter used in sunscreen products. Due to its extensive use, a significant level of OC is detected in marine and freshwater environments. Notably, the bioaccumulation of OC in aquatic biota may affect human health. In this study, the effect of OC on metabolism was investigated using the adipogenesis model of human bone marrow mesenchymal stem cells (hBM-MSCs). OC promoted adiponectin production during adipogenesis in hBM-MSCs compared to the vehicle-treated control (EC50, 29.6 µM). In target identification, OC directly bound to peroxisome proliferator-activated receptor (PPAR) γ (Ki, 37.8 µM). OC-bound PPARγ also significantly recruited nuclear receptor coactivator proteins SRC-1 (EC50, 54.1 µM) and SRC-2 (EC50, 58.6 µM). In the molecular docking simulation study, the optimal ligand-binding mode of OC suggested that OC is a PPARγ partial agonist. A competitive analysis with a PPARγ full agonist pioglitazone revealed that OC acted as a PPARγ partial agonist. OC altered the gene transcription profile of lipid-metabolism associated enzymes in normal human keratinocytes, primarily exposed human cells after the application of sunscreens. In conclusion, OC is a potential metabolic disrupting obesogen.

Discovery of a Novel Template, 7-Substituted 7-Deaza-4'-Thioadenosine Derivatives as Multi-Kinase Inhibitors.

The development of anticancer drugs remains challenging owing to the potential for drug resistance. The simultaneous inhibition of multiple targets involved in cancer could overcome resistance, and these agents would exhibit higher potency than single-target inhibitors. Protein kinases represent a promising target for the development of anticancer agents. As most multi-kinase inhibitors are heterocycles occupying only the hinge and hydrophobic region in the ATP binding site, we aimed to design multi-kinase inhibitors that would occupy the ribose pocket, along with the hinge and hydrophobic region, based on ATP-kinase interactions. Herein, we report the discovery of a novel 4'-thionucleoside template as a multi-kinase inhibitor with potent anticancer activity. The in vitro evaluation revealed a lead 1g (7-acetylene-7-deaza-4'-thioadenosine) with potent anticancer activity, and marked inhibition of TRKA, CK1δ, and DYRK1A/1B kinases in the kinome scan assay. We believe that these findings will pave the way for developing anticancer drugs.

Olig2 regulates p53-mediated apoptosis, migration and invasion of melanoma cells.

Melanoma is a disease with a high recurrence rate and poor prognosis; therefore, the need for targeted therapeutics is steadily increasing. Oligodendrocyte transcription factor2 (Olig2) is a basic helix-loop-helix transcription factor that is expressed in the central nervous system during embryonic development. Olig2 is overexpressed in various malignant cell lines such as lung carcinoma, glioma and melanoma. Olig2 is known as a key transcription factor that promotes tumor growth in malignant glioma. However, the role of Olig2 in melanoma is not well characterized. We analyzed the role of Olig2 in apoptosis, migration, and invasion of melanoma cells. We confirmed that Olig2 was overexpressed in melanoma cells and tissues. Reduction of Olig2 increased apoptosis in melanoma cells by increasing p53 level and caspase-3/-7 enzyme activity. In addition, downregulation of Olig2 suppressed migration and invasion of melanoma cells by inhibiting EMT. Reduction of Olig2 inhibited expression of MMP-1 and the enzyme activity of MMP-2/-9 induced by TGF-ß. Moreover, Olig2 was involved in the downstream stages of MEK/ERK and PI3K/AKT, which are major signaling pathways in metastatic progression of melanoma. In conclusion, this study demonstrated the crucial roles of Olig2 in apoptosis, migration, and invasion of melanoma and may help to further our understanding of the relationship between Olig2 and melanoma progression.

Discovery and Structure-Activity Relationships of Novel Template, Truncated 1'-Homologated Adenosine Derivatives as Pure Dual PPARγ/δ Modulators.

Following our report that A3 adenosine receptor (AR) antagonist 1 exhibited a polypharmacological profile as a dual modulator of peroxisome proliferator-activated receptor (PPAR)γ/δ, we discovered a new template, 1'-homologated adenosine analogues 4a-4t, as dual PPARγ/δ modulators without AR binding. Removal of binding affinity to A3AR was achieved by 1'-homologation, and PPARγ/δ dual modulation was derived from the structural similarity between the target nucleosides and PPAR modulator drug, rosiglitazone. All the final nucleosides were devoid of AR-binding affinity and exhibited high binding affinities to PPARγ/δ but lacked PPARα binding. 2-Cl derivatives exhibited dual receptor-binding affinity to PPARγ/δ, which was absent for the corresponding 2-H derivatives. 2-Propynyl substitution prevented PPARδ-binding affinity but preserved PPARγ affinity, indicating that the C2 position defines a pharmacophore for selective PPARγ ligand designs. PPARγ/δ dual modulators functioning as both PPARγ partial agonists and PPARδ antagonists promoted adiponectin production, suggesting their therapeutic potential against hypoadiponectinemia-associated cancer and metabolic diseases.

Benzophenone-3 and benzophenone-8 exhibit obesogenic activity via peroxisome proliferator-activated receptor γ pathway.

Benzophenone-3 (BP-3) and benzopenone-8 (BP-8) are commonly used ultraviolet (UV) filter ingredients in diverse sunscreen products. Recently, the obesogenic activity of avobenzone, a long wave UV A filter, was elucidated in the adipogenesis model of human bone marrow mesenchymal stem cells (hBM-MSCs). In this study, the obesogenic potentials of BP-3 and BP-8 were investigated because of their chemical similarity to avobenzone. During the adipogenesis in hBM-MSCs, BP-3 and BP-8 (EC50, 25.05 and 43.20 µM, respectively) potently promoted adiponectin secretion than avobenzone (EC50, 72.69 µM). In target identification, both BP-3 and BP-8 directly bound to peroxisome proliferator-activated receptor γ (PPARγ), which was associated with the recruitment of steroid receptor coactivator-2 (SRC-2). BP-3 functioned as a PPARγ full agonist whereas BP-8 was a PPARγ partial agonist. In addition, BP-3 and BP-8 significantly increased the gene transcription of PPARα, PPARγ, and major lipid metabolism-associated enzymes in human epidermal keratinocytes, a major target site of UV filters in human skin. This study suggests that BP-3 and BP-8 are obesogenic environmental chemicals similar to phthalates, bisphenols, and organotins.

Cyclin-Dependent Kinase 5 Inhibitor Butyrolactone I Elicits a Partial Agonist Activity of Peroxisome Proliferator-Activated Receptor γ.

Adiponectin is an adipocyte-derived cytokine having an insulin-sensitizing activity. During the phenotypic screening of secondary metabolites derived from the marine fungus Aspergillusterreus, a poly cyclin-dependent kinase (CDK) inhibitor butyrolactone I affecting CDK1 and CDK5 was discovered as a potent adiponectin production-enhancing compound in the adipogenesis model of human bone marrow-derived mesenchymal stem cells (hBM-MSCs). CDK5 inhibitors exhibit insulin-sensitizing activities by suppressing the phosphorylation of peroxisome proliferator-activated receptor γ (PPARγ). However, the adiponectin production-enhancing activities of butyrolactone I have not been correlated with the potency of CDK5 inhibitor activities. In a target identification study, butyrolactone I was found to directly bind to PPARγ. In the crystal structure of the human PPARγ, the ligand-binding domain (LBD) in complex with butyrolactone I interacted with the amino acid residues located in the hydrophobic binding pockets of the PPARγ LBD, which is a typical binding mode of the PPARγ partial agonists. Therefore, the adiponectin production-enhancing effect of butyrolactone I was mediated by its polypharmacological dual modulator activities as both a CDK5 inhibitor and a PPARγ partial agonist.

Selenium bioisosteric replacement of adenosine derivatives promoting adiponectin secretion increases the binding affinity to peroxisome proliferator-activated receptor δ.

N6-(3-Iodobenzyl)adenosine-5'-N-methyluronamide (1a, IB-MECA) exhibited polypharmacological characteristics targeting A3 adenosine receptor (AR), peroxisome proliferator-activated receptor (PPAR) γ, and PPARδ, simultaneously. The bioisosteric replacement of oxygen in 4'-oxoadenosines with selenium significantly increased the PPARδ-binding activity. 2-Chloro-N6-(3-iodobenzyl)-4'-selenoadenosine-5'-N-methyluronamide (3e) and related 4'-selenoadenosine derivatives significantly enhanced adiponectin biosynthesis during adipogenesis in human bone marrow mesenchymal stem cells (hBM-MSCs). The PPARδ-binding affinity, but not the A3 AR binding affinity, of 4'-selenoadenosine derivatives correlated with their adiponectin secretion stimulation. Compared with the sugar ring of 4'-oxoadenosine, that of 4'-selenoadenosine was more favorable in forming the South sugar conformation. In the molecular docking simulation, the South sugar conformation of compound 3e formed additional hydrogen bonds inside the PPARδ ligand-binding pocket compared with the North conformation. Therefore, the sugar conformation of 4'-selenoadenosine PPAR modulators affects the ligand binding affinity against PPARδ.

2-Phenyl-8-(1-phenylallyl)-chromenone compounds have a pan-PPAR modulator pharmacophore.

Adiponectin is an adipocytokine with insulin-sensitizing, anti-atherogenic, and anti-inflammatory properties. Adiponectin secretion-inducing compounds have therapeutic potential in a variety of metabolic diseases. Phenotypic screening led to the discovery that 5,7-dihydroxy-8-(1-(4-hydroxy-3-methoxyphenyl)allyl)-2-phenyl-4H-chromen-4-one (compound 1) had adiponectin secretion-inducing activity during adipogenesis in human bone marrow mesenchymal stem cells (hBM-MSCs). Compound 1 was originally reported to be an anti-cancer chemical isolated from natural honeybee propolis, and its adiponectin secretion-inducing activity was found in non-cytotoxic concentrations. In a target identification study, compound 1 and its potent synthetic derivative compound 5 were shown to be novel pan-peroxisome proliferator-activator receptor (PPAR) modulators. Molecular docking models with PPARs have indicated that the binding modes of chromenone compounds preferentially interacted with the hydrophobic ligand binding pocket of PPARs. In addition, chromenone compounds have been shown to result in different phenotypic outcomes in the transcriptional regulation of lipid metabolic enzymes than those of selective PPAR mono-agonists for PPARα, PPARγ, and PPARδ. In line with the pharmacology of adiponectin and PPAR pan-modulators, compounds 1 and 5 may have diverse therapeutic potentials to treat cancer and metabolic diseases.

A long-wave UVA filter avobenzone induces obesogenic phenotypes in normal human epidermal keratinocytes and mesenchymal stem cells.

Avobenzone is the most commonly used ultraviolet (UV) A filter ingredient in sunscreen. To investigate the biological activity of avobenzone in normal human epidermal keratinocytes (NHEKs), the genome-scale transcriptional profile of NHEKs was performed. In this microarray study, we found 273 up-regulated and 274 down-regulated differentially expressed genes (DEGs) in NHEKs treated with avobenzone (10 µM). Gene Ontology (GO) enrichment analysis showed that avobenzone significantly increased the DEGs associated with lipid metabolism in NHEKs. In addition, avobenzone increased the gene transcription of peroxisome proliferator-activated receptor γ (PPARγ) and fatty acid binding protein 4 in NHEKs, implicating that avobenzone may be one of the metabolic disrupting obesogens. To confirm the obesogenic potential, we examined the effect of avobenzone on adipogenesis in human bone marrow mesenchymal stem cells (hBM-MSCs). Avobenzone (EC50, 14.1 µM) significantly promoted adipogenesis in hBM-MSCs as its positive control obesogenic chemicals. Avobenzone (10 µM) significantly up-regulated mRNA levels of PPARγ during adipogenesis in hBM-MSCs. However, avobenzone did not directly bind to PPARγ and the avobenzone-induced adipogenesis-promoting activity was not affected by PPARγ antagonists T0070907 and GW9662. Therefore, avobenzone promoted adipogenesis in hBM-MSCs through a PPARγ-independent mechanism. This study suggests that avobenzone functions as a metabolic disrupting obesogen.

Adiponectin-Secretion-Promoting Phenylethylchromones from the Agarwood of Aquilaria malaccensis.

The therapeutic potential of adiponectin regulation has received interest because of its association with diverse human disease conditions, such as diabetes, obesity, atherosclerosis, and cancer. Phenylethylchromone derivatives from Aquilaria malaccensis-derived agarwood promoted adiponectin secretion during adipogenesis in human bone marrow mesenchymal stem cells, and 5,6-dihydroxy-2-(2-phenylethyl)chromone (1) was identified as a new chromone derivative. A target identification study with the most potent adiponectin-secretion-promoting phenylethylchromones, 6-methoxy-2-(2-phenylethyl)chromone (3) and 7-methoxy-2-(2-phenylethyl)chromone (4), showed that they are PPARγ partial agonists. Therefore, the diverse therapeutic effects of agarwood are associated with a PPARγ-mediated adiponectin-secretion-promoting mechanism.

Kojyl cinnamate esters are peroxisome proliferator-activated receptor α/γ dual agonists.

Adiponectin is an adipocytokine with insulin-sensitizing, anti-inflammatory, anti-atherosclerotic, and anti-aging properties. Compounds with the ability to promote adiponectin secretion are of interest for the development of anti-aging drugs to improve skin-aging phenotypes. In the phenotypic assay to measure adiponectin secretion during adipogenesis in human adipose tissue-derived mesenchymal stem cells (hAT-MSCs), kojyl cinnamate ester derivatives increased adiponectin secretion. A target identification study showed that the kojyl cinnamate ester derivatives competitively bound to peroxisome proliferator-activated receptor α/γ (PPARα/γ). The upregulation of adiponectin production induced by kojyl cinnamate ester derivatives was significantly correlated with PPARα and PPARγ binding activities. Kojyl cinnamate ester derivatives significantly increased the transcription of genes encoding cholesterol and fatty acid synthesizing enzymes in hAT-MSCs. Notably, the kojyl cinnamate esters upregulated the gene transcription of lipid metabolic enzymes in human epidermal keratinocytes, which are important in the integrity of skin permeability barrier. In addition, the kojyl cinnamate esters that function as PPARα/γ dual modulators inhibited ultraviolet B irradiation-induced inflammation in human epidermal keratinocytes. Therefore, kojyl cinnamate ester derivatives are a novel class of PPARα/γ dual agonists with the potential to improve skin-aging phenotypes.

2-Formyl-komarovicine promotes adiponectin production in human mesenchymal stem cells through PPARγ partial agonism.

Adiponectin is a major adipocytokine secreted from mammalian adipocytes. Relatively low expression of adiponectin is associated with various human metabolic diseases and some cancers. Adiponectin-secreting compounds have therapeutic potential for these diseases. Adipogenesis of human bone marrow-mesenchymal stem cells (hBM-MSCs) has been used as a phenotypic assay to find adiponectin secreting compounds. In a phytochemical library screen, 2-formyl-komarovicine, 1-(quinolin-8-yl)-1,3,4,9-tetrahydro-2H-pyrido[3,4-b]indole-2-carbaldehyde, isolated from Nitraria komarovii was identified as a potential adiponectin-secreting compound. To validate the results of the impure phytochemical, we synthesized 2-formyl-komarovicine. The synthetic 2-formyl-komarovicine significantly promoted adiponectin production during adipogenesis in hBM-MSCs. In a target identification experiment, 2-formyl-komarovicine bound to peroxisome proliferator-activated receptor γ (PPARγ) in a concentration-dependent manner. Notably, 2-formyl-komarovicine competitively inhibited the adiponectin-promoting activity of a full PPARγ agonist, troglitazone, in hBM-MSCs, which is a pharmacological feature of a partial agonist. The ligand-docking model showed that 2-formyl-komarovicine interacted with the hydrophobic pocket of the PPARγ ligand-binding domain, but lacked an interaction to stabilize helix H12, which is one of the major binding themes of PPARγ partial agonists. We concluded that 2-formyl-komarovicine provides a novel pharmacophore for PPARγ partial agonists to increase adiponectin production.